- What is the best way to represent the shape of a large population of measurements?

a. A histogram

b. A frequency curve

c. A bell-shaped curve

d. None of the above

B

- In a frequency curve, how do you interpret the height of the curve at any particular point?

a. The number of individuals in the population having that particular measurement.

b. The proportion of individuals in the population having that particular measurement.

c. The height of the individuals in the population represented by that particular point.

D. None of the above.

D

- What is another term for measurements following a ‘normal distribution’?

a. The measurements follow a ‘bell-shaped curve.’

b. The measurements follow a ‘normal curve.’

c. The measurements follow a ‘Gaussian curve.’

d. All of the above

D

- Which of the following describes the entire area underneath a frequency curve?

a. The entire area is 1 or 100%.

b. The entire area is equal to the total number of individuals in the population.

c. The entire area is equal to the total percentage of individuals in the population with the measurement being studied.

d. None of the above.

A

- Which of the following measurements likely has a normal distribution, at least approximately?

a. Weights of 10-year old boys.

b. IQ scores of 12 graders.

c. Nationwide scores on the SAT (Scholastic Achievement Test).

d. All of the above.

D

Which of the following describes measurements that have a normal distribution?

a. The majority of the measurements are somewhere close to the average.

b. The farther away you move from the average, the fewer individuals will have those more extreme values for their measurements.

c. The mean of the measurements is located in the middle of the bell-shaped curve.

d. All of the above.

D

- Suppose your score on the GRE (Graduate Records Exam) was at the 90th percentile. What does that mean?

a. You got 90% of the questions right.

b. 90% of the other students scored lower than you did.

c. 10% of the other students scored lower than you did.

d. None of the above.

B

- Which of the following is not true about a standard normal curve?

a. It is symmetric.

b. It has a mean of 0 and standard deviation of 1.

c. Its measurements are z-scores.

d. All of the above are true.

D

- Suppose one individual in a certain population had a z-score of −2. Which of the following is true?

a. This is a bad thing because the individual is below average.

b. This individual’s measurement is 2 standard deviations below the mean.

c. This individual’s original measurement was a negative number.

d. All of the above are true.

B

- {Entrance exam narrative} [Normal table or calculator required.] Bob’s original score was 130 and Jill’s standard score was +1.5. What percentage of the students taking this exam had scores that fell between Bob and Sue’s scores?

a. 16%

b. 93%

c. 77%

d. Not enough information to tell.

C

- {Men’s heights narrative} Using the Empirical Rule, 95% of adult males should fall into what height range?

a. They should be between 64 and 76 inches tall.

b. They should be close to the height that is 95% of the mean. That is, 66.5 inches, plus or minus 2 standard deviations.

c. They should be at or below the 95th percentile, which is 74.92 inches.

d. None of the above.

A

- {Men’s heights narrative} Using the Empirical Rule, 68% of adult males should fall into what height range?

a. Between 67 and 73 inches tall.

b. At or below 68 inches tall.

c. Between 70 and 73 inches tall.

d. None of the above.

A

- What do you need to check for first, before using the Empirical Rule to describe a population?

a. You need to check whether or not the population is large.

b. You need to check whether or not the population is Empirical.

c. You need to check whether or not the population follows a bell-shaped curve.

d. None of the above. The Empirical Rule works for any population.

C

- Suppose a population generally follows a normal curve, except that one of the measurements on this curve falls more than 3 standard deviations above the mean. What would you call this value?

a. An extreme outlier.

b. An error. All the values should lie within 3 standard deviations of the mean.

c. A value that has a 99.7% chance of occurring, because of the Empirical Rule.

d. None of the above.

A